Cannula extension and connector apparatus



Dec. M, 1969 w. E. QUINTQN 3,484,121

CANNULA EXTENSION AND CONNECTOR APPARATUS.

Filed Sept. 26, 1966 .I Il I `'vmlllllllllll` l Ill! 4 ZA Mr:

TTOF/YEYS United States Patent O 3,484,121 CANNULA IEXTENSIUN AND CGNNECTR APPARATUS Wayne E. Quinton, 3051 44th Ave. W., Seattle, Wash. 98199 Filed Sept. 26, 1966, Ser. No. 582,129 Int. Cl. F161 33/00, 3.7/00, 47/00, 49/00 US. Cl. 285-242 7 Claims ABSTRACT 0F THE DISCLOSURE A cannula extension device is disclosed which includes a tubular member having a tapered end for insertion into a cannula to provide a turbulent free juncture with the inner wall of the cannula. A protective member secured to the extension device, and in one embodiment integrally formed there-with, covers the end of the cannula to provide a bacteriologically clean joint. A cylindrical shunt connector is described which receives two extension devices and holds the ends thereof in firm end-to-end sealing relationship so that leakage and turbulence of the blood is avoided.

Much work has been done in recent years in the field of dialysis making use of machines referred to as artificial kidneys which cleanse the blood of a person who has suffered kidney failure or malfunction. The process requires repeated access to the patients circulatory system and thus a cannula has been developed which is inserted into the patients blood vessels. Thus the circulatory system of the patient can be easily connected and disconnected to and from the dialysis equipment. A bacteriologically clean interconnection must be obtained and in addition such interconnection should be easily effected without special tools. The need for a bacteriologically clean cannula connection assembly has been further emphasized with the advent of home dialysis equipment since the sterile atmosphere of a hospital normally is not obtainable in the home of the patient. It is well known that clotting of the blood must be avoided and therefore it is desirable to have an interconnection assembly which does not interrupt the laminar dow of the blood.

Accordingly, it is an object of the present invention to provide a novel cannula connection apparatus.

A further object of the present invention is to provide an improved bacteriologically clean cannula interconnection apparatus. An additional object of the present invention is to provide a cannula extension assembly adapted to provide a smooth transition from the cannula to the interior of the extension assembly so that clotting of the blood is avoided.

A further object of the present invention is to provide an improved cannula connection assembly including cornponents which are easily sterilized and easily connected and disconnected Without the need for special tools or parting forceps. Another object of the present invention is to provide a novel shunt connector assembly for interconnecting a pair of the improved cannula extension assemblies of the present invention so that a sterile and smooth end-to-end joint is provided between such cannula extensions. Another object is to provide a leak proof shunt connector which can be used as as sterile disposable unit and which is easily assembled yet held together by a positive lock which avoids unintentional disconnection.

In accordance with the teachings of the present invention an extension assembly is provided which has an inside part in the configuration of a smooth tubular member with one end of the walls thereof tapered for connection to a cannula. The opposite end of the tubular portion is made with a dat end wall to permit accurate end- 3,484,121 Patented Dec. 16, 1969 ICC to-end engagement with an identical extension assembly in a manner which avoids turbulence of the blood at the interconnecting faces. The part is shaped such that the tubular portion is reentrant into the cannula connected to the patients blood vessel with an over-lapping portion of the extension assembly being disposed on the Outside 0f the cannula. A bacteriologically clean extension is thus provided for the cannula with the joint between the cannula and the cannula extension assembly being such that a smooth transition is provided between the interior of the extension assembly and the interior of the cannula. The protruding end of the assembly is in the form of a tubular extension which is readily and easily sterilized.

The shunt connector assembly includes a cylindrical member having a central axial bore of a diameter equal to the outside diameter of the protruding end of the extension assembly, with the length of the bore being equal to twice the length of such protruding end. Thus two of the extension assemblies when inserted into opposite ends of the connector will have their protruding ends in contact with each other. The connector also has enlarged open ends adapted to fit over the exterior of the two extension assemblies. The protruding ends are of deformable material so that the same is easily forced into sealing engagement with circular depressions around the periphery of the extension assemblies. Thus a iirm mechanical as well as a bacteriologically clean joint is provided. The parts in contact with the blood are preferably made of a non-clotting material, one example of which is Teflon (polytetraliuoroethylene). In one embodiment the interior of the parts is made of Teflon while the exterior is made of a relatively low cost and substantially stronger material such as nylon.

Additional objects and advantages of the invention will be more readily understood from the following description of illustrative preferred embodiments.

FIGURE 1 is a cross-sectional view of one embodiment of the complete connection assembly shown as attached to the ends of a pair of cannulas.

FIGURE 2 is a cross-sectional isometric view of an extension unit similar to the ones shown in FIGURE l but made in one piece.

FIGURE 3 is a cross-sectional isometric view of a shunt connector similar to the one shown in the assembly of FIGURE l but made from a single block of material.

FIGURE 4 is a cross-sectional isometric view of another extension Unit similar to those of FIGURES 1 and 2 but with a majority of the unit made from a low cost material such as nylon and the interior blood-containing portion made from a smooth material such as Teflon.

FIGURE 5 is an illustration of a preferred connector with one half of the connector being illustrated in cross section.

Referring now to the drawing and in particular to FIGURE l, a first embodiment of the invention will be seen to include a pair of cannula extension assemblies 10 and 2Q which are interconnected by a shunt connector assembly Sil. The cannula extension assemblies are illustrated as being connected to portions of the cannulas 11 and 21 which are generally made of an elastic material such as silicone rubber. One such material in present use is that produced by the Dow-Corning Company under their trademark Silastio The extension assembly 10 includes an inner cylindrical member 12 having a central longitudinal or axial bore therethrough of a diameter equal to the inner diameter of the cannula 11. The leftwardly protruding end 12A of the member 12 has a beveled end 12B which fits into the right end of the cannula 11 with the cannula 11 being expanded near its right end upon insertion of the beveled end 12B. The arrangement is such that a smooth transition between the interior of the cannula 11 and the cylindrical member 12 is formed. It is found that with this type of juncture between the member 12 and the cannula 11 turbulence of the blood is minimized.

The rightwardly extending portion 12C of the member 12 is of uniform cylindrical configuration with the right end thereof being accurately machined so that a fiat end is provided. The diameter of the central body portion of the cylindrical member 12 is greater than either of the protruding cylindrical portions 12B or 12C and is provided with a circumferential groove 12D of semicircular configuration. A sleeve-like tubular member 13 completes the extension assembly by being formed about the enlarged central cylindrical portion of the member 12 and deformed into the semicircular groove 12D. The sleeve portion 13 extends over the exterior of the cannula 11 and is form-fitted thereon. In practice it has been found that a sleeve member 13 can be preferably made from a heat shrinking plastic material such as polyolefin which can be placed around the cylindrical member 12 and over the cannula 11 and then heat shrunk into the groove 12D and about the cannula 11. Thus a bacteriologically clean as well as a mechanically strong connection is provided between the extension assembly and the cannula 11. In the embodiment shown in FIG- URE 1 the extension assembly cylindrical member 12 is made from a single piece of material such as Teflon (polytetrafluoroethylene).

A right cannula extension 20 is identical to the extension assembly 10 and thus includes a cylindrical body member 22 with a central axial bore and protruding cylindrical extensions 22A and 22C with the extension 22A having beveled ends 22B which fit into the cannula 21. A sleeving portion 23 similar to the sleeving portion 13 previously described completes the right cannula assembly 20. It should be noted that the ends of the two cannulas 11 and 21 are cut with a fiat surface which fits against the perpendicular wall portions defined by the sides of the enlarged cylindrical portions of the members 12 and 22.

The assembly of FIGURE 1 includes a shunt connector 30 made from the cylindrical member 31 having a central axial bore of a diameter equal to the outer diameter of the protruding cylindrical portions 12C and 22C on the cannula extensions 10 and 20. The axial length of the member 31 is equal to the combined lengths of the cylindrical extensions 12C and 22C so that the flatted ends of the extensions 12C and 22C come into abutting engagement inside the bore of the member 31. This also results in the fiat surfaces 12E and 22E engaging the ends of member 31 to further insure a well seated joint. The shunt connector 30 is completed by the external sleeving member 32 which is secured to the internal member 31 by being deformed into the external circumferential groove 31D provided about the center of the inner coupling member 31. The sleeving member 32 is firmly fixed to the member 31, as for example by being heat shrunk into the groove 31D. The sleeve 32 protrudes in an axial direction from each end of the member 31 and extends over the exterior of the sleeving members 13 and 23. The sleeve 32 may be made from the same material as the sleeving members 13 and 23 and extends beyond the circumferential grooves 12D and 22D of the extension assemblies so it can be temporarily deformed toward the grooves 12D and 22D to provide leak proof and bacteriologically clean seals between the extension assemblies and the shunt connector assembly. In the embodiment illustrated in FIGURE l retaining ties in the form of sterile thread sections 24 and 25 are firmly tied about the opposite extremities of the sleeving member 32 to hold the shunt connector and extension assemblies 10 and 20 together as a single unit. The coupling member 31 can be made from a single block of a material such as Teflon.

It should be noted in FIGURE 1 that a smooth transition is provided between the extension assemblies and each of the cannulas and also that the flatted ends of the extensions 12C and 22C of the extension assemblies come into uniform engagement. Thus the flow of blood from the cannula 11 to the cannula 21 occurs with little or no turbulence. The configuration of the various components is such that a reinforced joint is provided which permits handling of the parts without danger of deforming the parts or the inner lumen of the cannulas. The joint is formed to be not only mechanically strong but also bacteriologically clean. It should be noted that the sleeve portions 13 and 23 overlap the cannulas and thus once the extension assemblies have been attached to the cannulas the protruding portions 12C and 22C present cylindrical surfaces which are readily sterilized.

In the embodiment of the invention illustrated in FIG- URE 1 the cannula sections 11 and 21 can be securely held in position on the extension assemblies 10 and 20 by a suitable adhesive to further insure a strong and sterile joint. Any microscopic openings in the assembly are readily filled by using a small amount of silicone grease. In the embodiment of the cannula extension illustrated in FIGURE 2 the entire extension assembly is made from a single block of material and is provided with raised ribs 1-6 and 17 on the leftwardly protruding cannula receiving portion 12A. The arrangement is such that when the cannula section 11 is forced over the protruding end 12A the members 16 and 17 will deform the cannula section and act as unidirectional locking devices to firmly hold the cannula in position with the end thereof held tightly against the enlarged cylindrical section of the extension assembly. The extension assembly illustrated in FIGURE 2 may be made from any strong material such as any of one of a number of plastics or metal. so long as the blood engaging surfaces are made of a non-clotting material.

In FIGURE 3 an alternative embodiment of the shunt connector is illustrated as being formed from a single block of material. The member 40 of FIGURE 3 will be seen to have protruding thin-Walled cylindrical ends 41 and 42 with the tie members 43 and 44 being shown as having deformed the sections 41 and 42 into the shape of the mating semi-circular groove 12D of a cannula extension assembly such as that shown in FIGURE 2. As in the case of the embodiment of FIGURE 1, the main body of the shunt connector 40 has a central axial bore of a diameter equal to the outer diameter of the cylindrical extension 12C of the cannula extension assembly of FIGURE 2. The surfaces 40B and 40C are machined or cast to provide flat surfaces against which the ends 12E and 22E of the extension assemblies abut.

It is important that the material in contact with the blood be made from an appropriate substance which minimizes clotting of the blood. It has been found that at the present time the cost of such material is substantially greater while the strength is less than that of many other materials such as nylon which can be used to form strong mechanical joints. Thus in the embodiment of the invention illustrated in FIGURE 4 a cannula extension assembly 50 is seen to be made with a section of material such as Teflon in the form of a tubular member 53 disposed within a cylindrical member 52 made from a strong and low cost material such as nylon. The left end of the tubular member 53 is beveled as at 53A With the cylindrical member 52 having a beveled surface 52A which continues at the same angle as the surface 53A. Thus when the cannula section 11 is forced over the left end of the tubular member 53 and the tubular extension 52B of the member 52 a smooth transition from the interior of the cannula to the interior of the tubular member 53 is provided. The member 52 is provided with a circumferential semi-circular groove 52D similar to the one illustrated in the embodiment of the invention shown in FIGURES 1 and 2. Any suitable device Such as a tie, metal ring, or rubber band can thus serve to deform the ends 41 and 42 of the connector.

Referring now to FIGURE 5, a further preferred ernbodiment of the shunt connector of the present invention will be described. As in the embodiment of FIGURE 3, the shunt connector of FIGURE is adapted for use with two of the cannula extension assemblies such as shown in FIGURE 4. As such the connector of FIGURE 5 includes a central cylindrical body section 60 which is provided with a longitudinal axial bore 61. The entrance openings to the central axial bore are chamfered at 60A and 60B to facilitate entry of the end 51 of a cannula extension such as shown in FIGURE 4. It is also of importance to note in the embodiment of FIGURE 5 that the diameters of the outer ends of the axial bore indicated at 62 and 63 are slightly greater than the diameter of the tubular member 51 of the cannula extension of FIGURE 4 while the central portions of the axial bore indicated at 64 and 65 are of a diameter which is slightly less than the outer diameter of the cylindrical member 51. The arrangement is such that as the cannula extension is moved into the connector of FIGURE 5 the cylindrical extension 51 of the cannula extension assembly is slightly compressed due to the taper of the bore in the connector assembly. This insures a positive seal and a very strong mechanical joint.

In the embodiment illustrated in FIGURE 5 the opposite ends of the connector assembly include cylindrical sections 66 and 67 which are adapted to be disposed about the cylindrical body 52 of a cannula extension such as shown in FIGURE 4 with the at end surface of the cylindrical section 52 being disposed against the radial wall provided in the connector between the cylindrical sections 66 and 67 and the main cylindrical body 60. It has been found in practice that ease of assembly of the entire apparatus is of particular importance while at the same time a joint which does not tend to come apart is of equal or greater importance. Thus the connector of FIGURE 5 is provided with easily deformed end sections 69 and 70 which are generally in the shape of thin walled right circular cylinders each provided with a circumferential groove 71 and 72 and a corresponding aligned interior re-entrant circumferential section 73 and 74 adapted to meet with the circumferential groove 52D on the extension assembly of FIGURE 4. Four axial slots 75 and 76 are provided in each of the end circumferential sections 69 and 70 (one slot in each quadrant). The arrangement is such that as the cylindrical section 52 of an extension assembly is positioned in the end of the connector shown in FIGURE 5 the four quadrants of the cylindrical member defined by adjacent slots in the ends thereof will be readily expanded and hence entry of the extension assembly into the connector assembly will be facilitated. When the cylindrical section 52 has been completely seated within the connector of FIGURE 5, the circumferential grooves 71 and 72 of the connector assembly will be aligned with the circumferential grooves 52D of the extension assemblies. After the parts have been thusly assembled, the O rings 75 and 76 (tubular bands of rubber) are moved from their positions shown in FIGURE 5 into the respective circumferential grooves 71 and 72 to thereby firmly hold the cannula extensions within the connector. To prevent accidental removal of the O rings, the connector assembly is provided with enlarged flanges 77 and 78 at its opposite ends and thus there is little likelihood of the O rings being slid thereover accidentally.

The length of the cylindrical section 51 (FIGURE 4) is made slightly longer than the distance from the extreme end of the connector to the radial wall 60C (FIGURE 5) so that the first contact between the parts during assembly is made by the end of section 51 engaging the chamfered wall 60A (or the wall 60C and then into 60A). This provides accurate initial parts alignment. The length of section 51 however is slightly less than the distance from the outer end of the connector to the bottom of the chamfered wall 60A (the start of the bore at 62) and 6 thus the enlarged section 52 of the extension member (FIGURE 4) engages the interior of the enlarged end 69 for further guidance during assembly.

It has been found in practice that the cannula extension is advantageously secured to the cannula by means of an adhesive, and thus the extension member shown in FIGURE 4 is provided with an air vent 52E in the wall thereof. This permits the escape of air trapped in the space between the cannula and cannula extension during connection of the two. In practice it is found that this hole then becomes filled with the adhesive which holds the cannula and extension together, with the hole becoming filled after the trapped air has escaped.

It is found in practice that if the two O rings come into contact with each other, it is diicult or awkward to separate the two in order to place them into their respective locking positions. Thus the connector of FIGURE 5 is provided with a central external circumferential enlargement 79 which is positioned between the O rings 75 and 76 and holds them apart.

The interior bore of the enlarged cylindrical ends 69 and 70 can advantageously be provided with slight tapers with the taper extending from the largest diameter at the outer end to a slightly smaller diameter opening in the vicinity of the cylindrical portions 66 and 67. This further facilitates assembly of the apparatus. It is found in practice that by providing the angled surfaces 80 and 81 on the exterior of the connector the O rings 75 and 76 are easily rolled up the inclines provided thereby and thence into the circumferential locking grooves. A snap type of locking action occurs as the stretched rubber rings are moved into locking position. Thus the entire operation of connecting the parts is performed with ease and with little detailed attention or skill being required. The resulting connection, however, has little tendency to come apart accidentally.

While the relative dimensions of the various parts will obviously vary in accordance with a specific requirement, it should be mentioned that in one embodiment of the invention constructed in accordance with the teachings of FIGURE 5 and FIGURE 4 the outer diameters of the cylindrical sections 51 (FIGURE 4) were 0.135 inch, and the bore of the connector tapered from a diameter of 0.136 inch at the positions indicated at 62 and 63 to a central diameter of 0.134 inch in the center of the connector. It has been found that the devices of FIGURE 5 can be readily fabricated by means of injection molding using a suitable material such as nylon.

There has thus been disclosed an improved cannula extension and connector apparatus with a completed assembly including a pair of extension assemblies and a shunt connector. While the invention has been described by reference to the presently preferred embodiments thereof it should be understood that the same was done only for purpose of teaching the invention.

What is claimed is:

1. A cannula interconnection apparatus for providing a detachable joint between first and second thin walled cannulas comprising in combination.: means defining first and second cannula extensions each including a tubular member having a first section with the end thereof beveled for insertion into a cannula, a second section with the end thereof substantially at, and an enlarged body section disposed between the said ends thereof, said tubular members having an axial bore of a uniform inner diameter substantially equal to the inner diameters of the cannulas to provide a smooth ow path, and each said enlarged section having a wall section extending radially outward from said bore; first and second thin Walled cylindrical sealing members respectively engaged in sealing relationship with the said enlarged body sections of said extensions and disposed about and parallel to said first sections of said tubular members to thereby define first and second cylindrical cavities for the receipt of cannulas; a connector member having an axial bore 7 and an enlarged body section defining first and second radial walls, said bore being of a length substantially equal to the sum of the lengths of said second sections of said tubular members to thereby hold said fiat ends in engagement with each other when the enlarged wall sections of said tubular members are respectively engaged with said walls; and sealing means connected to said connector member and disposed about said enlarged body sections of said tubular members.

2. Apparatus as defined in claim 1 wherein said last named means includes an elongated sleeving member disposed about the body sections of said tubular members and said connector member.

3. Apparatus as defined in claim 1 wherein said first and second thin walled sealing members are respectively integral parts of said tubular members.

4. Apparatus as defined in claim 1 wherein said enlarged body sections of said tubular members are each provided with circumferential external grooves, and releasable compression means disposed about said last named sealing means and aligned with said grooves to deform said sealing means into said grooves.

5. Apparatus as defined in claim 1 wherein said last named sealing means includes first and second thin walled cylindrical extensions of said body section of said connector member which define first and second cylindrical cavities at the opposite ends of said connector member adapted to have said body sections of said cannula extensions disposed therein.

6. Apparatus as defined in claim 5 wherein the said extensions of said body section of said connector member are each provided with a plurality of longitudinal slots.

7. A cannula extension apparatus comprising an elongated tubular member having an axial bore of substantially uniform diameter throughout its length, a first end section with a uniform beveled surface in the shape of a frustrum of a cone for insertion into the end of a cannula, a second tubular end section having a constant wall thickness and a fiat end, an enlarged cylindrical body section which is an integral part of and is disposed between said end sections with said end sections extending in opposite directions from the body section, said body section having a circumferential sealing groove provided around the periphery thereof, and a thin walled cylindrical section extending axially from said body section disposed about said first end section and displaced from said lirst end section in a radial direction by a distance corresponding to the wall thickness of a cannula to, be disposed about said first end section, the side of said body section adjacent said second tubular end section being a at wall having said second end section as the only part extending from said wall.

References Cited UNITED STATES PATENTS 382,468 5/1888 Haley 285-243 767,893 8/ 1904 Jewell 285-243 1,329,121 1/1920 Hachman 285-371 X 2,031,825 2/ 1936 Eastman 285-243 3,112,748 12/1963 Colburn 128-350 3,211,475 10/1965 Freed et al 285-260 X 3,338,598 8/1967 Kurtz 285-55 3,204,988 9/1965 Ouderkirk et al. 285-423 X FOREIGN PATENTS 1,004,427 11/ 1951 France. 1,296,895 5/ 1962 France.

914,803 7/1954 Germany.

829,703 3/ 1960 Great Britain.

317,669 5/1934 Italy.

THOMAS F. CALLAGHAN, Primary Examiner U.S. Cl. X.R. 

